RESPONDING FOR REWARDING BRAIN-STIMULATION - COCAINE AND ISRADIPINE PLUS NALTREXONE

Rats, fixed with chronically indwelling electrodes for electrical intr acranial stimulation (ICS) of the lateral hypothalamus, were taught to press a bar for ICS. Once pressing rates became stable, during daily 20-min sessions, rats were given cocaine (5 or 20 mg/kg) before the se ssions. When given daily, cocaine consistently enhanced rates of press ing. When a combination of small doses of isradipine (e.g., 1 mg/kg) a nd naltrexone (3 mg/kg) were given before cocaine administration, the combination blocked cocaine's enhancement of pressing for ICS. The com bination, however, neither reduced rates of pressing below those obser ved under placebos (i.e., baseline conditions) nor reduced rates when no cocaine was given. Naltrexone and isradipine (in the dose used in t he combination) by themselves did not block cocaine's effects. This pr ofile of effects indicates that a combination of isradipine and naltre xone is apt to be useful in treating cocaine use disorders. (C) 1998 E lsevier Science Inc.